The present invention relates to illumination for an inspection system, and more particularly to a sealed dome light for a machine vision inspection system.
Camera based inspection systems are commonly used in industrial settings to automate the inspection of products. Camera based inspection systems, commonly referred to as “machine vision” systems, can identify defects or contamination at a fast rate and for very small parts. High intensity LEDs provide proper illumination for high-speed camera equipment to take pictures of products being manufactured or assembled, often as the product passes by one or more particular points on an assembly line. The pictures are analyzed by a computer to determine if there are any defects in the product.
In order for the computer to analyze the photographs, it is desirable that the illumination of the product be nearly uniform for all of the pictures taken by the camera. This uniformity in lighting helps prevent the computer from misinterpreting the photographs due to changed lighting conditions. Illumination can be provided in various forms including direct illumination, ring illumination, horizontal illumination, coaxial illumination, and dome illumination. Dome illumination, in particular, works very well for inspecting irregularly shaped objects. Dome lights are used to create even lighting on shiny or uneven surfaces.
Dome illuminators or lights generally include a hemispherical dome that overlies an object to be inspected. A light source, such as a ring of LEDs, is located within the dome. The dome light includes a central opening that provides a viewing window for an associated camera. The camera takes pictures of the products positioned below the dome light. Dome lights used in industrial settings, including for the production of consumables, can get dirty, dusty, and/or contaminated and require cleaning to continue providing proper illumination. One issue with cleaning dome lights is that the LEDs, though seated within their ring, are not protected and may be exposed to water or other cleaning fluids. Thus, it would be desirable to provide a dome light that is sealed to protect the LEDs and other interior components, making the dome light readily cleanable.